When using a component mounter (component insertion assembly device) to insert a lead of an electronic component into a through-hole of a circuit board, for example, as disclosed in patent literature 1 (WO2013-183123), a lead of an electronic component is inserted into a through-hole of a circuit board by using a suction nozzle or chuck device or the like of a mounting head of the component mounter to pick up the electronic component, moving above the circuit board, positioning the lead tip (lower end) of the electronic component directly above the through-hole of the circuit board, and lowering the electronic component. Here, because the position of the electronic component held by the mounting head shifts for each electronic component, before the electronic component held by the mounting head is moved above the circuit board, it is moved to an imaging position above a component imaging camera, the lead tip of the electric is imaged from below by the camera, and by performing image processing of the image using conventional pattern matching, the center position of the lead tip is recognized, then, based on the recognition result, the position deviation of the electronic component is corrected, and the lead of the electronic component is positioned directly above the through-hole of the circuit board.